Piston.



A. C. MASON & A. T. STURT.

PlsToN.. APPLICATION FILED JULY 26. |916.

l ,275,064. Patented Aug. 6, 1918.

f L -M//VOR ,4X/5 al d. CMM j( LME/WHS v /l Fas? ma da Arron/v TED STATES PATENT OFFICE.

ARTHUR C. MASON AND AAI'JFIRJLD T. STURT, OF FLINT, MICHIGAN, ASSIGNORS TO CHEVROLET MOTOR COMPANY, OF WARE.

NEW YORK, N. Y., A CORPORATION OF DELA- PISTON.

. clear, and exact description thereof.

This invention relates to the construction of pistons designed primarily for use in internal combustion engines. The object l of the invention is to so form and construct a piston that it will be capable of expansion due to the heat in the cylinder of an internal combustion engine, and at the same time eliminate the danger of scoring the cylinder lwall especially at points adjacent to the piston pin holes, which is a more or less frequent occurrence in engines of this type of different construction. To this end I construct a piston the skirt of which in horizontal section is substantially elliptical in shape, the minor axis being in line with that of the piston pin, and the vmajor axis being perpendicular thereto.v The ring groove flanges, and the piston heady are substantially circular in cross-section, the diameters of which are slightly less thanlthe length ofthe minor laxisfofv--the section of the skirt. The diameters of the ring groove flanges in practice grow gradually less from the flange nearest the skirt to the head of the piston.

In practice, a piston, the skirt of which has a major axis equal to 3.685 isprovided with a minor axis of ..003 to .005

less in length than the major axis. We nd that a very eflicient Vconstructlon is to cause each radius of the minor axis to be .002less in length than the radius of the major axis.

` Referring to the drawings in which the same reference character indicates the same j part in the several views:

Figure 1 is asection of a piston and 'connecting rod, the connecting rod being shownv in elevation.

Fig. 2 is an end view of the piston looking in the direction of the arrow in Fig. 1.

Fig. 3 is an end view of -a piston looking in the directionof the arrow of Fig. 1, said piston being mounted in the cylinder, the po- Sition ofthe piston infthe cylinder being Specification of Letters Patent.

- Fig. 3'.

Patented Aug. 6, 1918.

Application led July 26, 1916. Serial N o. 111.474.

' merely conventionally shownin extreme proportion in the interest ofclearness.

The part marked 1 is the piston, 2 the connecting ro'd and 3 the piston pin, said connecting rod being secured to the pin by the usual split collar 4 with a screwthreaded bolt 5, the piston pin being mounted in the sleeves 6 and 6. 7 is the cylinder, the inner wall -of which is truly cylindrical. The major axis of the skirt 9 oi the piston lies between the lines a-b, and the minor axis lies between the lines c-al The piston ts the cylinder -at the extremities of the major axis with a conventional working clearance at X and Y, so that the piston will be guided truly in the cylinder during its reciprocation therein, as clearly shown in As hereinbefore described, the showing/jin Fig. 3 ofthe relative dimensions of the pisof the piston in line with the ton and cylinder is merely conventional and j greatly enlarged so as to more clearly illustrate the construction. j

The ring groove fianges 10, 11 and 12 are in plan and in horizontal cross-sectiontrue circles, the diameters of which, due to the fact that the head is subjected to the most heat, are less than the length of the'minor axis of the horizontal section of the skirt 9, and the diameter of the head 12 is slightly less than that of the liange 11, and the diam-- eter ofthe Hange 11 is slightly less than that of the flange 10.

By providing a piston the skirt of which is substantially elliptical in cross-section, we find in practice that the danger of scoring the vcylinder due to lunequal expansion, by 1 reason of the heat to which the metals ofthe piston and of the cylinder are subjected, is reduced to a minimum and is in eli'ect m'l.

- In operation, the thrust of the piston at the points X and Y upon the surface of the cylinder is resisted by the'cylinder wall and as a result of this action a distortion, both of the piston and the cylinder wall takes place, so that the piston is expanded along its minor axis and the diameter of the cylincler in line with the minor axis of the piston `is to some degree lessened, thereby enlarging the area of the surface contact of the piston and cylinder wall at the extremitiesv of the major axis of the piston.

rllhis construction produces a contact of the piston with the cylinder wall, which at all times is stable and the bearing is thus caused to widen as the piston is subjected to greater loads, and the piston and cylinder to greater heat, thereby causing an additional bearing surface, to compensate for the additional load on the piston, and the danger of scoring the cylinder wall is thus avoided.

As changes could be made within. the scope of our invention, We intend that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is:

l. An engine piston substantially elliptical in horizontal cross section in combination with la cylinder, having a substantially circular cross section.

2. An engine piston, the horizontal cross section of which is provided with a major and minor axis in combination with a cylinder having a substantially circular cross section. n

3. A piston, as set forth in claim l, in which the piston pin is substantially parallel with the minor axis.

A, The combination of an engine cylinder and its piston, saidpiston having major and minor axes in the horizontal cross-sec tion thereof tol provide clearance spaces between the piston and the portions oit the wall ot the cylinder opposite the extremities or the said minor axls.

5. An engine piston having a continuous or unbroken wearing surface whose diameter in one direction slightly exceeds the diameter at right angles thereto, both of said diameters lying in the same plane,

La7/acca 6. The combination with a cylinderof a piston therein, the horizontal section of which is substantially in the form of an ellipse, the major `axis of said ellipse being substantially equal to the diameter of the cylinder.

7. A piston, provided with a head having ring groove flanges, and a skirt, the said Ranges being substantially circular in hori- 'zontal cross-section, and the skirt being substantially elliptical in horizontal crosssection.

8. A piston as set forth in claim 7, in which the diameter of the cross section of the circular portion is less than the minor axis of the ellipse, the major axis of the ellipse being substantially equal to the diameter of the cylinder,

9. A piston as set forth in claim 8, in which the ring groove flanges have decreasing diameters, the flange of largest diameter being closest to the skirt.

l0. A piston provided with a head having ring groove flanges, and a skirt, the said flange being circular in horizontal crosssection, and the skirt being elliptical in horizontal cross-section, the diameter of the circular cross section being less than the minor axis of the ellipse.

ll. A piston provided with a head and skirt, the head being circular in horizontal cross-section and the skirtbeing elliptical in horizontal cross-section, the diameter of the circular cross-section being no longer than the length of the minor axis of the ellipse.

12. 'llhe combination of a piston and an yengine cylinder, one of which is substantially elliptical in horizontal cross-section, and the other of which is substantially circular in horizontal cross section.

13. lln combination, an inclosing envelop and an inclosed piston, the horizontal cross sectiony of the two being of substantially different area and shape, respectively.

ln witness whereof we have hereunto set our hands at the borough ot Manhattan, city, county, andv State oit New York, this 10th day of July, 1916.

ARTHUR C. MASON. ALFRED ,l. S'lllUR'l. lln presence of lsABEL R. RICHARDS, Errani, D. RAWN. 

